Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
insuperably is an adverb meaning "to an insuperable degree". It carries one recorded sense.
to an insuperable degree
“these various courses all seemed insuperably difficult to the student”
Definitions, synonyms and semantic relations for insuperably come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.